BF3·Et2O-mediated cascade cyclizations: Synthesis of schweinfurthins F and G

Nolan R. Mente, Jeffrey Neighbors, David F. Wiemer

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

(Chemical Equation Presented) The total synthesis of the natural stilbene (+)-schweinfurthin G (8) has been accomplished through a sequence based on an efficient cationic cascade cyclization. This cascade process is initiated by Lewis acid promoted ring opening of an epoxide and terminated through a novel reaction with a phenolic oxygen "protected" as its MOM ether. Several Lewis acids have been examined for their ability to induce this new reaction, and BF3·Et2O was found to be the most effective. The only major byproduct under these conditions was one where the expected secondary alcohol was found as its MOM ether derivative (e.g., 30). While this byproduct could be converted to the original target compound through hydrolysis, it also could be employed as a protected alcohol to allow preparation of a benzylic phosphonate (43) without dehydration of the secondary alcohol. The resulting phosphonate was employed in a Horner-Wadsworth-Emmons condensation with an aldehyde representing the right half of the target compounds, an approach complementary to previous studies based on condensation of a right-half phosphonate and a left-half aldehyde.

Original languageEnglish (US)
Pages (from-to)7963-7970
Number of pages8
JournalJournal of Organic Chemistry
Volume73
Issue number20
DOIs
StatePublished - Oct 17 2008

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Organophosphonates
Cyclization
Lewis Acids
Alcohols
Aldehydes
Ether
Byproducts
Condensation
Stilbenes
Epoxy Compounds
Dehydration
Hydrolysis
Oxygen
Derivatives
schweinfurthin G
schweinfurthin F

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

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abstract = "(Chemical Equation Presented) The total synthesis of the natural stilbene (+)-schweinfurthin G (8) has been accomplished through a sequence based on an efficient cationic cascade cyclization. This cascade process is initiated by Lewis acid promoted ring opening of an epoxide and terminated through a novel reaction with a phenolic oxygen {"}protected{"} as its MOM ether. Several Lewis acids have been examined for their ability to induce this new reaction, and BF3·Et2O was found to be the most effective. The only major byproduct under these conditions was one where the expected secondary alcohol was found as its MOM ether derivative (e.g., 30). While this byproduct could be converted to the original target compound through hydrolysis, it also could be employed as a protected alcohol to allow preparation of a benzylic phosphonate (43) without dehydration of the secondary alcohol. The resulting phosphonate was employed in a Horner-Wadsworth-Emmons condensation with an aldehyde representing the right half of the target compounds, an approach complementary to previous studies based on condensation of a right-half phosphonate and a left-half aldehyde.",
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BF3·Et2O-mediated cascade cyclizations : Synthesis of schweinfurthins F and G. / Mente, Nolan R.; Neighbors, Jeffrey; Wiemer, David F.

In: Journal of Organic Chemistry, Vol. 73, No. 20, 17.10.2008, p. 7963-7970.

Research output: Contribution to journalArticle

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